[patch V2 22/23] genirq/msi: Handle PCI/MSI allocation fail in core code

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

Get rid of yet another irqdomain callback and let the core code return the
already available information of how many descriptors could be allocated.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Tested-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
---
 drivers/pci/msi/irqdomain.c |   13 -------------
 include/linux/msi.h         |    5 +----
 kernel/irq/msi.c            |   29 +++++++++++++++++++++++++----
 3 files changed, 26 insertions(+), 21 deletions(-)

--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -95,16 +95,6 @@ static int pci_msi_domain_check_cap(stru
        return 0;
 }
 
-static int pci_msi_domain_handle_error(struct irq_domain *domain,
-                                      struct msi_desc *desc, int error)
-{
-       /* Special handling to support __pci_enable_msi_range() */
-       if (pci_msi_desc_is_multi_msi(desc) && error == -ENOSPC)
-               return 1;
-
-       return error;
-}
-
 static void pci_msi_domain_set_desc(msi_alloc_info_t *arg,
                                    struct msi_desc *desc)
 {
@@ -115,7 +105,6 @@ static void pci_msi_domain_set_desc(msi_
 static struct msi_domain_ops pci_msi_domain_ops_default = {
        .set_desc       = pci_msi_domain_set_desc,
        .msi_check      = pci_msi_domain_check_cap,
-       .handle_error   = pci_msi_domain_handle_error,
 };
 
 static void pci_msi_domain_update_dom_ops(struct msi_domain_info *info)
@@ -129,8 +118,6 @@ static void pci_msi_domain_update_dom_op
                        ops->set_desc = pci_msi_domain_set_desc;
                if (ops->msi_check == NULL)
                        ops->msi_check = pci_msi_domain_check_cap;
-               if (ops->handle_error == NULL)
-                       ops->handle_error = pci_msi_domain_handle_error;
        }
 }
 
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -286,7 +286,6 @@ struct msi_domain_info;
  * @msi_check:         Callback for verification of the domain/info/dev data
  * @msi_prepare:       Prepare the allocation of the interrupts in the domain
  * @set_desc:          Set the msi descriptor for an interrupt
- * @handle_error:      Optional error handler if the allocation fails
  * @domain_alloc_irqs: Optional function to override the default allocation
  *                     function.
  * @domain_free_irqs:  Optional function to override the default free
@@ -295,7 +294,7 @@ struct msi_domain_info;
  * @get_hwirq, @msi_init and @msi_free are callbacks used by the underlying
  * irqdomain.
  *
- * @msi_check, @msi_prepare, @handle_error and @set_desc are callbacks used by
+ * @msi_check, @msi_prepare and @set_desc are callbacks used by
  * msi_domain_alloc/free_irqs().
  *
  * @domain_alloc_irqs, @domain_free_irqs can be used to override the
@@ -332,8 +331,6 @@ struct msi_domain_ops {
                                       msi_alloc_info_t *arg);
        void            (*set_desc)(msi_alloc_info_t *arg,
                                    struct msi_desc *desc);
-       int             (*handle_error)(struct irq_domain *domain,
-                                       struct msi_desc *desc, int error);
        int             (*domain_alloc_irqs)(struct irq_domain *domain,
                                             struct device *dev, int nvec);
        void            (*domain_free_irqs)(struct irq_domain *domain,
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -538,6 +538,27 @@ static bool msi_check_reservation_mode(s
        return desc->pci.msi_attrib.is_msix || desc->pci.msi_attrib.can_mask;
 }
 
+static int msi_handle_pci_fail(struct irq_domain *domain, struct msi_desc 
*desc,
+                              int allocated)
+{
+       switch(domain->bus_token) {
+       case DOMAIN_BUS_PCI_MSI:
+       case DOMAIN_BUS_VMD_MSI:
+               if (IS_ENABLED(CONFIG_PCI_MSI))
+                       break;
+               fallthrough;
+       default:
+               return -ENOSPC;
+       }
+
+       /* Let a failed PCI multi MSI allocation retry */
+       if (desc->nvec_used > 1)
+               return 1;
+
+       /* If there was a successful allocation let the caller know */
+       return allocated ? allocated : -ENOSPC;
+}
+
 int __msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
                            int nvec)
 {
@@ -546,6 +567,7 @@ int __msi_domain_alloc_irqs(struct irq_d
        struct irq_data *irq_data;
        struct msi_desc *desc;
        msi_alloc_info_t arg = { };
+       int allocated = 0;
        int i, ret, virq;
        bool can_reserve;
 
@@ -560,16 +582,15 @@ int __msi_domain_alloc_irqs(struct irq_d
                                               dev_to_node(dev), &arg, false,
                                               desc->affinity);
                if (virq < 0) {
-                       ret = -ENOSPC;
-                       if (ops->handle_error)
-                               ret = ops->handle_error(domain, desc, ret);
-                       return ret;
+                       ret = msi_handle_pci_fail(domain, desc, allocated);
+                       goto cleanup;
                }
 
                for (i = 0; i < desc->nvec_used; i++) {
                        irq_set_msi_desc_off(virq, i, desc);
                        irq_debugfs_copy_devname(virq + i, dev);
                }
+               allocated++;
        }
 
        can_reserve = msi_check_reservation_mode(domain, info, dev);